The present invention is directed generally to a strong metal complexing resin for ion exchange columns. More particularly, the invention is related to an ion exchange resin prepared by copolymerizing diphosphonic acid groups with acrylonitrile, styrene and/or divinylbenzene to form a polymeric resin for preferentially removing heavy metal contaminants in a highly acidic solution.
A variety of far reaching environmental protection statutes and regulations have significantly increased the need for effective and efficient means for removal of a wide spectrum of metal contaminants from aqueous based wastes or contaminated waterways. In addition, specific industries, such as the nuclear industry and electroplating industry, generate substantial quantities of water based effluent which are heavily contaminated with undesirable metal ions. The removal of metal ion contaminants from waste streams is often made difficult due to the strongly acidic nature of the waste effluent. Under such acidic conditions prior art metal complexing resins perform poorly to remove or recover such metals or have selectivity for only a very few types of metal ions. While phosphonic acids have been known to have the ability to complex with metal ions generally, there has been no demonstrated ability to allow selective removal of the chelated metal ions which is essential for selectivity of metal ion type as well as removal from the ion exchange resin.
It is therefore an object of the invention to provide an improved metal complexing resin for ion exchange columns.
It is also an object of the invention to provide a novel metal complexing resin and method of manufacture from copolymerization of diphosphonic acid groups with acrylonitrile, styrene and/or divinylbenzene.
It is an additional object of the invention to provide an improved method of preferentially removing toxic metal ions relative to alkaline and alkaline earth ions from strongly acidic water based wastes.
It is a further object of the invention to provide a novel product and method of manufacture of a sulfonated copolymer of diphosphonic acid group with acrylnitrile and styrene and/or divinylbenzene.
It is another object of the invention to provide an improved method of manufacturing a desired end product resin of narrow size distribution and uniform shape.
It is yet an additional object of the invention to provide a novel variety of copolymerization procedures involving copolymerizing vinylidene diphosphonic ester, a R.sub.2 C=CR.sub.2 group where R is a combination of electron donating/electron withdrawing groups, a divinyl to trivinyl crosslinking agent and a porogen in combination with an initiator, such as benzoyl peroxide.
It is still a further object of the invention to provide an improved ion exchange resin and method for removing actinide metal ions in III, IV and VI oxidation states and transition and post transition metals from highly acidic and highly basic waste solutions.